Biological measurement probe, biological optical measurement instrument using the same, and brain function measurement instrument

ABSTRACT

The present invention provides a biological measurement probe readily wearable on a biological surface having a large curvature and a measurement technique of simultaneously measuring the blood circulation dynamic change accompanying the auditory/language/visual function activities of a subject (especially baby) and brain waves. A biological measurement probe having illuminating means for illuminating a subject through a first optical waveguide and light collecting means for collecting light illuminated from the illuminating means and propagated through the subject through a second optical waveguide, has first and second guide members having passages through which the first and second optical waveguides are passed and fixing the first and second optical waveguides, and a base member connecting the first guide member to the second one, holding them, and forming a portion brought into contact with the subject.

TECHNICAL FIELD

The present invention relates to a biological measurement technique ofmeasuring the physiological change in biological tissue.

BACKGROUND ART

As a method for measuring the brain function of a baby, there isdisclosed a method for measuring brain waves generated from the brainstem in response to stimulation sounds. This method can mainly measurethe response of the brain stem and is difficult to measure thehigh-order functions controlled by the cerebral cortex.

As a method with light, a method for measuring the activities of thecerebral cortex is proposed. In biological measurement with light, aninstrument measuring the biological functions with visible to nearinfrared light is disclosed in Japanese Patent Application Laid-Open No.57-115232 or Japanese Patent Application Laid-Open No. 63-275323.Further, a proposal about a brain function image measurement techniqueby application of this measurement principle (optical topography) isdisclosed in Japanese Patent Application Laid-Open No. 9-98972.

These use light guide means, typically, an optical fiber, illuminatebiological tissue, and collect and measure the light scattered inbiological tissue in the positions several mm to several cm away(hereinafter, abbreviated as the scattering light in biological tissue).Based on the intensity of the measured scattering light in biologicaltissue, the concentration of absorber in biological tissue, typically,oxygenated Hemoglobin and deoxygenated Hemoglobin, or a valuecorresponding to the concentration, is obtained. When obtaining theconcentration of absorber or the value corresponding to theconcentration, the absorption characteristic of targeted absorbercorresponding to the wavelength of the illuminating light is used.Typically, when measuring a biological deep part, light which has awavelength within the range of 650 to 1300 nm and is high in biologicalpermeability, is used.

Such method with light is typically used for biological measurement of ahuman, in particular, an adult.

The method with light can also measure a baby in view of safety and maymeasure the high-order brain functions of the baby.

It has been, however, difficult to simultaneously measure the brain stemand the high-order functions accompanying the activities of the cerebralcortex of a baby. If this problem is solved, the low-order to high-orderbrain functional disorders will be able to be found at an early stage inbabyhood. The low-order to high-order brain functional disorders (forexample, auditory, language and visual disorders) are often found at theage of two or three and starting speaking. In such case, languageacquirement is delayed than normal, thereby requiring tremendous laborfor recovering the delay.

A social demand is significant in development of a technical method oran instrument capable of measuring the main brain functional disorders(of the visual, auditory and language functions) at an early stage.

For that purpose, the following two major technical problems (1) and (2)must be solved.

(1) A method for fixing an optical fiber used for the measurement ofbiological tissue with light

The measurement of biological tissue with light has means forillumination with light (hereinafter, abbreviated as illuminating means)and means for collecting light transmitted through biological tissue(hereinafter, abbreviated as light collecting means). As theilluminating means and the light collecting means, an optical waveguide,typically, an optical fiber or an optical fiber bundle, is often used. Aset of optical waveguides for illumination and light collection is aminimum unit indicating one measurement position (hereinafter,abbreviated as an illumination and light collection pair).

An instrument performing biological image measurement by setting aplurality of the minimum units is proposed in Japanese PatentApplication Laid-Open No. 9-98972. The distance between the illuminationposition and the light collection position of the illumination and lightcollection pair (hereinafter, abbreviated as the distance between theillumination and light collection pair) is changed by the size or depthof an area to be measured. The proposal of Japanese Patent ApplicationLaid-Open No. 9-98972 discloses an arrangement form in which an opticalwaveguide for illumination and an optical waveguide for light collectionare arranged alternately on the tops of a square grid so that thedistances between the illumination and light collection pairs areequally spaced. Using the arrangement form, one optical waveguide isshared among a plurality of illumination and light collection pairs soas to make image measurement by a small number of optical waveguides.The optical waveguides can be worn on biological tissue in a short time.

The arrangement form can be easily applied to a small area of biologicaltissue so as to be approximated on the plane of the biological tissue(for example, about 15 cm square for the head), but is difficult toapply to an area having a large curvature. In particular, the head shapeof a newborn or a baby has a large curvature so that the differenceamong individuals is large. When measuring a newborn or a baby, it isimpossible for the subject to wait quietly. There arises the problemthat the deviation of a probe due to movement must be suppressed, whichcannot be expected in an adult.

Means for measuring the brain functions of a newborn or a baby has beenlimited to an electroencephalogram. The spatial resolution of theelectroencephalogram is not very high, making it difficult to separateinformation on the brain stem as the center part of the brain and thecerebral cortex of the brain surface. On the contrary, a brain functionmeasurement method based on the measurement with light enablesnon-invasive measurement of the cerebral cortex related strongly to thehigh-order brain functions particularly developed in a human. It isexpected as a very effective method for recognizing the developmentprocess of the high-order functions. Although it is known to beeffective in principle, a biological measurement probe fixing waveguidesfor illumination and light collection has not been developed.

DISCLOSURE OF THE INVENTION

To construct a practical biological measurement probe for a newborn or ababy, the following points are required and will be listed below.

a) The character of flexibility:

A biological measurement probe to be used must be flexibly suitable to abiological surface having a curvature

b) Holding ability of the distance between waveguides for incidencedetection:

In a biological measurement probe to be used, the distance betweenwaveguides for incidence detection (to be exact, the distance betweenthe edges of waveguides for illumination detection, which will be, forconvenience, called the distance between incidence detection) must notbe changed over the allowable range to the shape having the differenceamong individuals so as to secure, together with the a), the characterof flexibility but the distance does not change.

c) Body movement follow-up ability:

A biological measurement probe to be used must not be deviated due tomovement to some degree.

d) Visibility of contact property:

A biological measurement probe to be used must have high visibility andeasily control the contact state so as to check the contact propertybetween an optical waveguide and a biological surface.

e) Comfortableness:

The head of a subject having low adaptability to environmental change,such as a newborn or a baby, must not be covered completely from theviewpoint of temperature change.

f) Pressure dispersibility:

A high pressure must not be applied to one point of a subject having thedelicate head, such as a newborn or a baby.

g) Shape holding ability:

To reduce a load given to a subject, a probe must be worn in a shorttime. It is thus necessary to easily change its shape and to hold itsbasic shape.

h) Wearability:

From the same reason as the g), means for easily fixing a probe isnecessary.

i) Suitability to the shape and size of fixing means:

Fixing means must be suitable to the head shape of a subject.

j) Pressurizing ability of fixing means:

Fixing means must give a suitable pressure.

k) The distance between illumination and light collection positionssuitable for the brain function measurement of a baby must be obtained.

(2) Brain function examination instrument for baby

To measure the brain functions of the entire brain of a baby, anexamination instrument capable of measuring light and brain waves isnecessary. Specific problems about this will be listed below.

a) A bed for examination, which is designed to arrange optical fibersand brain wave electrodes on the entire area of the head, is essential.An ordinary bed is difficult to fix a measurement probe on the back partof the head related to the visual function, which is a problem to besolved.

b) A stimulation (visual and auditory) presentation instrument must bearranged in a safe and efficient position.

The present invention has been made in view of the above points and anobject of the present invention is to provide a biological measurementprobe readily wearable on a biological surface having a large curvatureand a biological measurement technique using the same to enablemeasurement of the physiological change accompanying the activities ofthe head of a newborn or a baby, which has been difficult to measure.

To achieve the above object, solving means of the above technicalproblems (1) and (2) which have been performed in the present inventionwill be described below.

In (1), in the present invention, the optical waveguide fixing partconnecting part for connecting the edges of the optical waveguide forincidence and the optical waveguide for light collection and the contactsurface brought into contact with biological tissue are integrallyformed by a flexible member having a high friction coefficient. Thewaveguide support part fixing the optical waveguide is adhered by themember.

A flexible thin film member is buried into the member to secure both thecharacter of flexibility and inextensibility (to secure the character offlexibility but the distance does not change). Further, the optimumdistance between illumination and light collection positions so as toexperimentally increase the sensitivity of a brain function signal, isobtained.

To realize simultaneous making of the measurement of biological tissuewith light and the biological electric measurement, typically, brainwaves, fixing parts incorporate waveguides for the measurement ofbiological tissue with light and an electrode and an electric wire ofthe biological electric measurement.

In (2), in the present invention, sound, visual and language stimulationis given to a subject, and then, a measurement method with light and amethod for measuring brain waves are used to simultaneously measure thepresence or absence of brain functional disorders from the brain deeppart (the brain stem) to the brain surface (the cerebral cortex) of ababy.

In this case, the back part of the head on a bed for examination isreleased to support the head in the neck and the lower part of the backpart of the head. The visual and auditory stimulation instrument isarranged in the safe position in the examination space. The sameconstruction of substantially different sizes can also measure the brainfunction of an adult.

Representative construction examples of the present invention will belisted below.

A biological measurement probe according to the present invention havingilluminating means for illuminating a subject through a first opticalwaveguide and light collecting means for collecting light illuminatedfrom the illuminating means and propagated through the subject through asecond optical waveguide, has first and second guide members havingpassages through which the first and second optical waveguides arepassed and fixing the first and second optical waveguides, and a basemember connecting the first guide member to the second one, holdingthem, and forming a portion brought into contact with the subject.Further, in the construction, the base member is made of a material inwhich the character of flexibility and biological suitability are high.The biological measurement probe further has extensible members in thefirst and second guide members for allowing the first and second opticalwaveguides to be movable in the axial direction.

In the present invention, in the construction, the illuminating meansincludes a light source for illumination and a light source controlcircuit controlling an injected current to the light source, and thelight collecting means includes an optical detector and a detectionsignal circuit processing a detection signal obtained by the opticaldetector.

In the present invention, in the construction, the base member isprovided in its inside with an electrode for brain wave measurementtogether with the first optical waveguide and/or the second opticalwaveguide so as to simultaneously make the measurement with light andthe brain wave measurement.

Further, the present invention provides a biological optical measurementinstrument capable of measuring the psychological change in a subjectusing a biological measurement probe having illuminating means forilluminating the subject through an optical waveguide and lightcollecting means for collecting light illuminated from the illuminatingmeans and propagated through the subject through an optical waveguide,wherein the probe has first and second guide members having passagesthrough which the optical waveguide for illumination and the opticalwaveguide for light collection are passed and fixing the opticalwaveguides, a base member connecting the first guide member to thesecond one, holding them, and forming a portion brought into contactwith the subject, and extensible members in the first and second guidemembers for allowing the first and second optical waveguides to bemovable in the axial direction.

Furthermore, the present invention provides a brain function measurementinstrument having a biological optical measurement instrument capable ofmeasuring the psychological change in a subject using a biologicalmeasurement probe having illuminating means for illuminating the subjectthrough an optical waveguide and light collecting means for collectinglight illuminated from the illuminating means and propagated through thesubject through an optical waveguide, a brain wave measurementinstrument electrically measuring brain waves, a stimulation controllerhaving data about sound, voice, language and image given to the subjectand controlling them, and presenting means for reading data about thesound, voice, language and image and presenting them to the subject,wherein a brain function activity signal of the subject is measuredwhile presenting at least one of the sound, voice, language and imagetransmitted from the stimulation controller via the presenting means tothe subject. The present invention also provides a brain functionmeasurement instrument having the biological measurement probeconstructed-such that the base member is provided in its inside with anelectrode for brain wave measurement together with the first opticalwaveguide and/or the second optical waveguide so as to simultaneouslymake the measurement with light and the brain wave measurement andmeasuring a brain function activity signal of the subject by themeasurement with light and the brain wave measurement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of assistance in explaining a wearing example forwearing biological measurement probes on a subject according to thepresent invention;

FIG. 2 is a diagram of assistance in explaining a basic construction ofan embodiment of the biological measurement probes according to thepresent invention;

FIG. 3 is a diagram showing a modification pattern of optical waveguidefixing parts shown in FIG. 2;

FIG. 4 is a diagram of assistance in explaining an embodiment of a brainfunction measurement instrument according to the present invention;

FIG. 5 is a diagram of assistance in explaining a construction exampleof a subject fixing part in the brain function measurement instrumentaccording to the present invention;

FIG. 6 is a diagram of the subject fixing part shown in FIG. 5 whenviewed from slantly above;

FIG. 7( a) is a diagram showing the brain wave change of the brain stemof a newborn to simple sounds, which is measured using the instrumentshown in FIGS. 4 and 5, and FIGS. 7( b) and 7(c) are diagrams showingthe blood circulation dynamic changes in the brain;

FIG. 8 is a diagram showing the Hemoglobin (Hb) concentration changes inthe active brain with time when changing the distance betweenillumination and light collecting waveguides of the biologicalmeasurement probes according to the present invention;

FIG. 9 is a diagram of assistance in explaining another constructionexample of the biological measurement probes according to the presentinvention; and

FIG. 10 is a diagram of assistance in explaining a construction exampleof the biological measurement probe for simultaneously realizing themeasurement with light and the brain wave measurement according to thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below withreference to the drawings.

Using FIG. 1, a wearing example in which optical waveguide fixing partsof biological measurement probes based on the present invention are wornon a subject (here, the head) will be described first.

Optical waveguide fixing parts 1-1 and 1-2 shown in FIG. 1 are held byoptical waveguide fixing part holding parts 1-3 and 1-4. The opticalwaveguide fixing part holding parts 1-3 and 1-4 are made of extensiblebelts or strings 1-3-1, 1-3-2, 1-3-3, 1-4-1, 1-4-2 and 1-4-3, and theextensible belts or strings are connected at both edges of the opticalwaveguide fixing part holding parts 1-3 and 1-4.

The extensible belts or strings may be light in weight and be as thin aspossible so as to easily check the contact state of the opticalwaveguides. The present invention uses extensible cloth. Differentmaterials having the same function may be used.

Optical-waveguide fixing part holding part connecting parts 1-5 and 1-6are made for connecting the optical waveguide fixing part holding parts1-3 and 1-4. The shape and function of the optical waveguide fixing partholding part connecting parts 1-5 and 1-6 are decided by the followingreasons.

First, the size of biological tissue is to be measured has thedifference among individuals. The connection distance must be changed soas to cope with the difference among individuals. In the presentinvention, detachable cloth tapes are attached to both edges of theoptical waveguide fixing part holding parts 1-3 and 1-4 and both edgesof the optical waveguide fixing part holding part connecting parts 1-5and 1-6, enabling distance adjustment according to the circumferentiallength of the head.

Second, since the optical waveguide fixing part holding part connectingparts 1-5 and 1-6 are directly brought into contact with the skin of thesubject, the width and the subject contact surface must be considered.To avoid the concentration of pressure to the skin of the subject, theymay not be thin like the extensible belts or strings forming the opticalwaveguide fixing part holding parts 1-3 and 1-4 and must have a width tosome extent. The width is desirably between 1 and 4 cm. The contactsurfaces of the optical waveguide fixing part holding part connectingparts 1-5 and 1-6 with the subject are desirably of a soft material andhave a high friction coefficient (to prevent slipping). As the materialfor that, silicone rubber, sponge, rubber and other organic materialsmay be used. Needless to say, other materials having an equal functionmay be used.

When the optical waveguide fixing parts 1-1 and 1-2 are small, wearingby the above-described components is possible. When the opticalwaveguide fixing parts 1-1 and 1-2 are large, auxiliary holding partsdescribed below must be used to give a uniform pressure to the opticalwaveguides.

In the present invention, auxiliary holding parts 1-7-1-a to 1-7-5-a and1-7-1-b to 1-7-5-b are attached. Removable cloth tapes are attached tothe edges of the auxiliary holding parts 1-7-1-a to 1-7-5-a and 1-7-1-bto 1-7-5-b. The auxiliary holding parts 1-7-1-a and 1-7-1-b areconnected by adjusting the length according to the shape of the head ofthe subject. Similarly, other auxiliary holding parts are connected byadjusting the length between a and b. As the materials of the auxiliaryholding parts 1-7-1-a to 1-7-5-a and 1-7-1-b to 1-7-5-b, extensiblebelts or strings which are as thin as possible are used.

As in an optical waveguide 1-8, optical waveguides are passed throughall optical waveguide guides. The wearing procedure is done in order ofA→B→C for simple wearing.

The features of the optical waveguide fixing part holding part will belisted below.

1) The optical waveguide fixing part holding part can be readily andquickly worn.

2) The optical waveguide fixing part holding part can be suitable tovarious shapes and sizes of subject measurement portions.

3) The optical waveguide fixing part holding part can give a uniform andsuitable pressure to the skin of a subject.

The optical waveguide fixing part holding part has various shapesaccording to measurement portions. The points forming the opticalwaveguide fixing part holding part are as follows.

1) The optical waveguide fixing part holding part is divided into aplurality of parts to be connected at wearing. (When measuring theentire brain, four planes of two planes of the side parts of the head,one plane of the front part of the head, and one plane of the back partof the head are measured.)

2) Length adjustment can be made in the connection part.

3) An extensible belt or string is used.

To realize the 1) and 2), a detachable cloth tape is used. To realizethe 3), an extensible cloth or rubber is used.

FIG. 2 shows optical waveguide fixing parts in an embodiment of abiological measurement probe of the present invention used for thewearing example shown in FIG. 1. Basically, they are constructed by arepeated pattern. FIG. 2 shows an example of the optical waveguidefixing parts when 9 (=3×3) optical waveguides are fixed. The upperdiagram shows only the optical waveguide fixing parts. The A-A′ sectionshown in the lower diagram shows a diagram in which optical waveguides2-5 and covers 2-4 are worn.

The optical waveguide 2-5 is movable in the vertical direction (alongthe axial direction of an optical waveguide guide 2-1 in the drawing) byan extensible member 2-6, typically, springs or sponges. The extensiblemember 2-6 is interposed in an extensible member retainer 2-7 adhered tothe cover 2-4 and the optical waveguide 2-5.

The optical waveguide fixing part basically has the optical waveguideguide 2-1, a base 2-2 for connecting and holding the optical waveguideguides, and a thin film or wire 2-3. The optical waveguide guide 2-1 ismade of a hard material, typically, plastic. The base 2-2 for connectingand holding the optical waveguide guides is made of a flexible materialhaving high biological suitability, typically, silicone. The thin filmor wire 2-3 is made of a plastic material, typically, a PET film. Thebase 2-2 for connecting and holding the optical waveguide guides is madeusing a die. It takes a long time for hardening. The optical waveguideguide member 2-1 is arranged during the hardening to fix the base 2-2for connecting and holding the optical waveguide guides and the opticalwaveguide guide 2-1. The thin film or wire 2-3 is buried into the base2-2 for connecting and holding the optical waveguide guides or isadhered to its surface during the hardening.

The optical waveguide fixing part is integrally molded and has thecharacter of flexibility, inextensibility and biological suitability.All the members 2-1 to 2-5 are desirably added black color or a coloringmatter absorbing illuminating light or visible light for suppressing theinfluence of stray light.

In FIG. 2, the end surfaces of the optical waveguides 2-5 brought intocontact with a subject are illustrated to be at the same level as thesubject contact surface of the base 2-2. In view of the hardness of thebase 2-2 and the extensibility of the extensible members 2-6, they areadjusted to be in the positions which give no discomfort feeling to thesubject.

The optical waveguides 2-5 are connected to light sources 2-9 and adetector 2-10 in a biological optical measurement instrument 2-8,respectively. In this example, only two light sources and one detectorare illustrated. In this embodiment, since the illumination positionsand the light collection positions are arranged alternately in thevertical and horizontal directions, there are provided four lightsources and five detectors. When the illumination positions and thelight collection positions are reversed, there are provided five lightsources and five detectors. The illumination positions and the lightcollection positions are set to 3×3 as a basic construction example. Theconstruction can be easily extended to a pattern of 4×4 or 3×5 or bereduced by erasing of unnecessary portions.

FIG. 9 shows another construction example of the biological measurementprobes according to the present invention and shows a constructionexample in which the optical waveguide fixing parts shown in theabove-described embodiment include light sources 2-9 necessary forillumination, light source control circuits 2-11 controlling an injectedcurrent, a detector 2-10 necessary for optical detection, and adetection signal circuit 2-12 amplifying a detection signal andperforming current-voltage conversion.

Depending on the construction of the light source 2-9 and the detector2-10 can reduce the number of parts by serving as a cover 2-4.

The light source control circuit 2-11 is connected to a biologicaloptical measurement instrument 2-8 for performing mutual communicationof necessary information on an injected current and a control signal viaa signal and power line 2-13. The detection signal circuit 2-12 isconnected to the biological optical measurement instrument 2-8 forperforming mutual communication of necessary information on a detectionsignal and setting of an amplification factor via the signal and powerline 2-13. The light source control circuit 2-11, the detection signalcircuit 2-12 and the biological optical measurement instrument 2-8incorporate communication devices to be made wireless by removing anylines other than necessary lines such as power lines.

The optical waveguide 2-5, the light source 2-9 and the detector 2-10are joined to each other. To attenuate light as noise for a measurementwavelength, such as visible light, a color filter is interposed in thejoint parts as necessary.

When applying such construction to the head, the light source detectoris arranged directly on biological tissue so that the optical waveguidesavoid hair, which provides a significant effect.

The base member as shown in FIGS. 2, 3 (described later) and 9 is holedso as not to keep in heat. An electrode for biological electricmeasurement (such as brain waves) can be provided therein. Inconsideration of the wearability, the optical waveguide for themeasurement of biological tissue with light is desirably integrated withthe electrode and wire for the biological electric measurement. Whenthey are integrated with each other, both are generically an energytransmission member, including the signal and power line of the exampleof FIG. 9.

FIG. 10 shows a construction example of a biological measurement probefor simultaneously realizing the measurement with light and the brainwave measurement according to the present invention (Only part of FIG. 2is shown.).

An optical waveguide 2-5 is provided with an electrode 2-14 for brainwave. The middle part of the electrode 2-14 is holed to bring the endsurface of the optical waveguide 2-5 into contact with a subjectsurface. An electric wire 2-15 from the electrode for brain wave to thebiological electric measurement instrument is wired along the opticalwaveguide 2-5 connected to the biological optical measurementinstrument. When a thin film or wire 2-3 in a base 2-2 is constructed byan electric wire circuit, a signal from the electrode 2-14 istransmitted by an electric wire or circuit 2-16 in the base 2-2. Aplurality of electrodes 2-14 provide an electric wire bundle of theelectric wires or circuits 16 which is connected from the base 2-2 viaan external electric wire bundle 2-17 to the external biologicalelectric measurement instrument.

As a modification, the electrode 2-14 is not provided in the opticalwaveguide 2-5 and is provided on the subject on the base 2-2 and the lowsurface brought into contact with the subject.

The features of the optical waveguide fixing part will be listed below.

1) Since the connecting member is made of a very soft material, theoptical waveguide fixing part can be suitable to an arbitrary shape.

2) Since the edges of the optical waveguides are connected to eachother, the distance between the optical waveguides is not changed on thesubject contact part: This contributes to making the light penetrationdepth in the measurement portions constant and acquirement of aspatially uniform signal. As shown in FIG. 2, when the distance betweenthe middles of the optical waveguides is 30 mm for manufacture, in thecase of being brought into contact with the curved surface in anarbitrary shape, the distance between the edges of the opticalwaveguides is held 30 mm.

3) Since the connecting member has a suitable friction coefficient,there is no deviation when body movement occurs.

4) Since the unnecessary portion of the connecting part is holed, thevisibility for checking the contact property of the optical waveguide ishigh.

5) There is no wasteful material in the unnecessary portion of theconnecting member. Ventilation can be made so that the skin of a subjectis not sweaty, which provides high comfortableness.

6) Only the edge of the optical waveguide gives no pressure to the skinsurface of a subject and pressure can be given in a large area. Each ofthe optical waveguide fixing part gives pressure by cushion so that painto the subject is very little.

FIG. 8 shows the measured results using the biological measurement probeshown in FIG. 10 and shows the Hemoglobin (Hb) concentration changes inthe active brain with time when changing the distance between theillumination and light collection waveguides. The vertical axisindicates the Hb concentration changes and the horizontal axis indicatestime. In the drawing, the dotted line indicates the concentrationchanges of oxygenated Hb (oxy-Hb) carrying oxygen, the dashed lineindicates the concentration changes of deoxygenated Hb (deoxy-Hb) inwhich oxygen is apart, and the solid line indicates values correspondingto the concentration changes of total Hb (total-Hb) as the total of theoxy-Hb concentration changes and the deoxy-Hb concentration changes.

In FIGS. 8( a) and 8(b), measurement is made simultaneously. A babysubject hears conversation in its mother tongue recorded onto a tapeduring the stimulation period. From this result, the signal of thedistance between the illumination and light collection waveguides of 30mm shown in FIG. 8( b) is larger than that of the distance between theillumination and light collection waveguides of 20 mm shown in FIG. 8(a). It is desirable to set the distance between the illumination andlight collection waveguides of 30 mm or more (That is, one side of agrid is 30 mm or more).

FIG. 3 shows a modification pattern of the optical waveguide fixingparts shown in FIG. 2. The square grid pattern shown in FIG. 2 can beused for a biological surface without any disorder. When there is anobstacle on the side part of the head or an ear, it cannot be arranged.In this case, it must be modified to a shape for avoiding the obstacle.In the pattern shown in FIG. 3, the second row is deviated to the upperside (in this case, 1 cm), and an ear can be arranged under the deviatedportion. When making such modification, the basic grid shape may berhombus (including square) so that all the distances between theillumination and light collection positions are constant. The basicconstruction is the same as FIG. 2 and the description is omitted. Thelower diagram shows the A-C section of the upper diagram.

The features of the present invention are advantageous for general useand are not limited to measurement of a baby. While holding thecomponents, the size and the arrangement of the optical waveguides arechanged for application to measurement of the head of an adult and inmuscles other than the head.

The instrument construction using the biological measurement probesaccording to the present invention will be described.

FIG. 4 shows an embodiment of a brain function examination instrumentbased on the present invention. Measurement is made in the state that asubject (for example, a baby) 4-1 lies quietly in a bed or incubator4-2. A plurality of optical fibers 4-3 (the solid lines) and brain waveelectrodes and signal lines 4-4 (the dotted lines) are worn on the headof the baby. The optical fibers include an optical fiber forillumination illuminating the skin of the head with light from the lightsource thereabove, and an optical fiber for light collection collectingthe scattering light transmitted through biological tissue and guidingit to the detector. One area is measured by each combination of them.

Typical illuminating light is near infrared light of near 800 nm havinga high biological permeability. From a value of the near infrared lightabsorbed into the biological tissue, an amount corresponding to theHemoglobin (Hb) concentration changes (Herein, the concentration refersto an Hb molecule weight in a unit tissue.) can be measured. Hb includesoxy-Hb carrying oxygen and deoxy-Hb in which oxygen is apart. When theyare separated for measurement, two suitable wavelengths are selected formeasurement. The total-Hb concentration changes as the total of theoxy-Hb concentration changes and the deoxy-Hb concentration changescorrespond to the change in blood volume.

It is known that there is a close relation between the brain functionactivities of an adult, the change in blood volume, the oxy-Hbconcentration changes and the deoxy-Hb concentration changes(hereinafter, generically called blood circulation dynamic change). Whenthe activity of the brain function occurs, metabolism is accelerated inthe local area in the brain serving as the function to supply oxygen tothe area. The blood volume and the oxy-Hb concentration are locallyincreased to decrease the deoxy-Hb concentration. The change in bloodvolume, the oxy-Hb concentration changes and the deoxy-Hb concentrationchanges are measured to recognize the brain function activities of anadult. It has been known that by a method with near infrared light, thebrain function activities of an adult can be measured or imaged (seeJapanese Patent Laid-Open Application No. Hei 9-98972).

There has not been a method for measuring the blood circulation dynamicchange accompanying the brain activities of a newborn or a baby withoutputting anesthesia. The relation between the brain activities of a babyand the blood circulation dynamic change is unknown. The brainactivities themselves are also unknown. In the method with light of thisembodiment, the optical fibers 4-1 are only worn on the head.Measurement can be made without putting anesthesia.

Brain waves have already been widely used clinically. The auditory brainstem reaction generated when a sound is heard is effective for findingthe auditory disorder at an early stage.

The biological optical measurement instrument mainly measures thecerebral cortex related to the high-order functions. Theelectroencephalogram measures brain waves generated from the brain stemand the nerve activities of the brain in which the portion cannot bespecified relatively. It is difficult to totally decide the braindisorders by either one of them.

In the present invention, a brain function measurement instrument 4-5integrally incorporates the measurement instrument with near infraredlight and the brain wave measurement instrument. They may be separatedas necessary. The brain function measurement instrument 4-5 is connectedto a plurality of the optical fibers 4-3 and electrodes and signal lines4-4 and incorporates a plurality of light sources and optical detectorsand brain wave potential measurement instruments. The brain functionmeasurement instrument 4-5 performs chronological processing and imagingof the blood circulation dynamic change in biological tissue and brainwaves and displays them on a display device 4-6.

An auditory/language/visual stimulation controller 4-7 is an instrumentcontrolling auditory/language/visual stimulation given to a baby. Theauditory/language/visual stimulation controller 4-7 writes a pluralityof sounds for language/auditory stimulation (beep sounds or clicksounds), voices (voices not as languages), languages (voices aslanguages) and image data (flashing, checker pattern and animation) asanalog or digital data. The sound, voice, language and image data aretransmitted in arbitrary timing to read and present the sounds, voicesand languages by one or more speakers and/or headphones 4-8. An imagedisplay device 4-10 displays the image data. The speaker and/orheadphone 4-8 and the image display device 4-10 are fixed in the bed orincubator 4-2. Various arrangement positions thereof can be considered.An example will be described later using FIG. 5.

The timing and time in which the sound, voice, language and image dataare transmitted from the auditory/language/visual stimulation controller4-7 and the kinds of the selected sound, voice, language and image dataare written into the brain function measurement instrument 4-5. Thebrain function measurement instrument 4-5 may instruct the timing andthe kinds of sound, voice, language and image given as stimulation andthe stimulation controller 4-7 may select the written sound, voice andlanguage corresponding to the instruction to output them as signals. Itis important that the brain function measurement instrument 4-5 be insynchronization with the auditory/language/visual stimulation controller4-7 by arbitrary means.

Based on the sound, voice and language from the speaker and/or headphone4-8 and the image presented on the image display device 4-10, thelanguage/auditory/visual functions are active so that the bloodcirculation dynamic change occurs in the brain. The blood circulationdynamic change is written into the brain function measurement instrument4-5. During measurement, the signal is displayed on the display device4-6. At the completion of all measurements, the processing is performedagain and the result is displayed on the display device 4-6. Two or moredifferent signals are displayed on the same screen and the samespace-time scale. The user can easily understand the signals.

When the biological measurement probe as shown in FIG. 10 is used, thesignal of the measurement with light and the electric measurement signalsuch as brain wave can be simultaneously measured. The processingresults of both signals are displayed on the display device 4-6 by agraph or an image.

FIG. 5 shows a diagram of a form in which the speaker and/or headphone4-8 and the image display device 4-10 are arranged in the bed orincubator 4-2, which is viewed from the side.

The bed or incubator 4-2 has a form to surround the subject 4-1, asshown in the drawing, and is made of transparent plastic to be seen fromthe inside. The subject 4-1 lies quietly on a slant subject fixing part4-11 to be comfortably measured. A subject legs support part 4-11-1 isfixed onto the subject fixing part 4-11 to be interposed between thelegs of the subject 4-1 for preventing the subject 4-1 from beingslipped down from the subject fixing part 4-11.

The speakers and/or headphones 4-8 are buried into both sides of thehead fixing part of the subject fixing part 4-11. When allowing thesubject to hear different sounds simultaneously in the right and leftears, the headphones are more desirable than the speakers.

The image display device 4-10 is fixed onto the position not immediatelyabove the subject 4-1 in the bed or incubator 4-2 using an image displaydevice fixing part 4-12. This arrangement is made in consideration ofsafety. Even if the image display device 4-10 is dropped, the subject4-1 will not be injured. Since the subject 4-1 must lie slantly, theslant subject fixing part 4-11 is necessary.

The speaker and/or headphone 4-8 and the image display device 4-10 areconnected to a stimulation controller 4-18 (for example, anauditory/language/visual stimulation controller) by signal lines 4-13-1to 4-13-2. When they are connected via a connector 4-14, they can beeasily disconnected. Their positions can be easily changed.

The optical fibers and the brain wave electrodes used for the brainfunction measurement are connected via a connector 4-16 to a brainfunction measurement instrument 4-17 by optical fibers and brain wavesignal lines 4-15.

FIG. 6 shows a construction example of the subject fixing part 4-11 whenviewed from slantly above. The subject legs support part 4-11-1 and asubject head support part 4-11-2 are provided on the subject fixing part4-11. The subject legs support part 4-11-1 is interposed between thelegs of the subject for preventing the subject from being slipped downfrom the slant subject fixing part 4-11.

The subject head support part 4-11-2 is arranged to support the neck tothe lower side of the back part of the head. As shown in the drawing, itis constructed to be width controllable, angle controllable and movableup and down. This shape can release the back part of the head and easilyattach the brain function measurement probes. When the subject fixingpart is slant, the display device for visual presentation need not beplaced immediately above the subject.

FIG. 7 shows the brain wave change and the blood circulation dynamicchanges of a newborn accompanying sounds, which are measured using theinstrument shown in FIGS. 4 and 5. FIG. 7( a) shows addition averagesignals of the brain waves of the brain stem to simple sounds whenallowing the newborn to hear the simple sounds (click sounds of 200 ms)with repetition of about 1000 times. When the auditory function is notabnormal, the brain waves having 6 to 7 peaks within 10 ms after hearingthe sound as the reaction of the brain stem, are observed, as shown inthe drawing.

The graphs of FIGS. 7( b) and 7(c) show the blood circulation dynamicchanges in the brain accompanying the reaction of the cerebral cortexwith the simple sounds and conversation. The vertical axis of the graphsof FIGS. 7( b) and 7(c) indicates values corresponding to the total-Hb,oxy-Hb and deoxy-Hb concentration changes. The horizontal axis thereofindicates time. The solid line indicates total Hb, the dotted lineindicates oxy-Hb, and the dashed line indicates deoxy-Hb.

The results of FIGS. 7( b) and 7(c) show data obtained by measuring theposition 1.5 cm above from the ear hole on the left side part of thehead of the newborn. In FIGS. 7( b) and 7(c), 35 seconds of astimulation period of 15 seconds, 5 seconds before the stimulationperiod and 15 seconds after the stimulation period are extracted as oneblock for each stimulation. The stimulation is repeated 10 times inFIGS. 7( b) and 7(c). Ten blocks are addition averaged to obtainchronological data of the blood circulation dynamic change.

Of the results, in FIG. 7( a), the auditory signals are transmitted atleast from the ears to the brain stem of the subject, indicating normalreaction. The signal transmission from the brain stem to the cerebralcortex is difficult to be specified by the brain waves. It is decided bythe result of the measurement with light capable of measuring thereaction of the blood circulation dynamic change accompanying theactivity of the cerebral cortex. With the simple sounds, a significantreaction does not occur in the cerebral cortex, as shown in FIG. 7( b).The reason is because the cerebral cortex controlling the high-orderfunctions is not very active with the simple sounds. As shown in FIG. 7(c), however, when hearing complicated sounds such as language(conversation), the cerebral cortex of the newborn is very active andrecognizes the language. From this result, the auditory and languagefunctions of the subject perform normally.

The present invention will be summarized as follows.

1) A biological measurement probe having illuminating means forilluminating a subject through a first optical waveguide and lightcollecting means for collecting light illuminated from the illuminatingmeans and propagated through the subject through a second opticalwaveguide, having first and second guide members having passages throughwhich the first and second optical waveguides are passed and fixing thefirst and second optical waveguides, and a base member connecting thefirst guide member to the second one, holding them, and forming aportion brought into contact with the subject.

2) The biological measurement probe according to the construction of the1), wherein the base member is made of a material in which the characterof flexibility and biological suitability are high.

3) The biological measurement probe according to the construction of the1), further having extensible members in the first and second guidemembers for allowing the first and second optical waveguides to bemovable in the axial direction.

4) The biological measurement probe according to the construction of the1), wherein the first and second guide members are arranged on the basemember to be alternate on the top positions of a square grid shape or arhombus grid shape.

5) The biological measurement probe according to the construction of the1), wherein the portion of the base member brought into contact with thesubject consists of a plurality of divided plane-structure members, andthe plane-structure members are connected through flexible members.

6) The biological measurement probe according to the construction of the1), wherein the illuminating means includes a light source forillumination and a light source control circuit controlling an injectedcurrent to the light source, and the light collecting means includes anoptical detector and a detection signal circuit processing a detectionsignal obtained by the optical detector.

7) The biological measurement probe according to the construction of the1), wherein the base member is provided in its inside with an electrodefor brain wave measurement together with the first optical waveguideand/or the second optical waveguide so as to simultaneously make themeasurement with light and the brain wave measurement.

8) A biological optical measurement instrument capable of measuring thepsychological change in a subject using a biological measurement probehaving illuminating means for illuminating the subject through anoptical waveguide and light collecting-means for collecting lightilluminated from the illuminating means and propagated through thesubject through an optical waveguide, wherein the probe has first andsecond guide members having passages through which the optical waveguidefor illumination and the optical waveguide for light collection arepassed and fixing the optical waveguides, a base member connecting thefirst guide member to the second one, holding them, and forming aportion brought into contact with the subject, and extensible members inthe first and second guide members for allowing the first and secondoptical waveguides to be movable in the axial direction.

9) The biological optical measurement instrument according to theconstruction of the 8), wherein the illuminating means includes a lightsource for illumination and a light source control circuit controllingan injected current to the light source, the light collecting meansincludes an optical detector and a detection signal circuit processing adetection signal obtained by the optical detector, and the light sourcecontrol circuit and the detection signal circuit are controlled viacommunication means, respectively.

10) A brain function measurement instrument having a biological opticalmeasurement instrument capable of measuring the psychological change ina subject using a biological measurement probe having illuminating meansfor illuminating the subject through an optical waveguide and lightcollecting means for collecting light illuminated from the illuminatingmeans and propagated through the subject through an optical waveguide, abrain wave measurement instrument electrically measuring brain waves, astimulation controller having data about sound, voice, language andimage given to the subject and controlling them, and presenting meansfor reading data about the sound, voice, language and image andpresenting them to the subject, wherein a brain function activity signalof the subject is measured while presenting at least one of the sound,voice, language and image transmitted from the stimulation controllervia the presenting means to the subject.

11) A brain function measurement instrument, wherein the biologicalmeasurement probe according to the 7) is used to measure a brainfunction activity signal of the subject by the measurement with lightand the brain wave measurement.

12) A brain function measurement instrument having a biological opticalmeasurement instrument having illuminating means for illuminatingbiological tissue and light collecting and detecting means forcollecting and detecting light transmitted through the biologicaltissue, a brain wave measurement instrument measuring brain waves, asound stimulation controller having a plurality of data about sound,voice and language, a speaker or headphone presenting the sound, voiceand language to a baby subject, a visual stimulation controller having aplurality of data about image, and an image display device presentingthe image to the subject, wherein a brain function activity signal ofthe subject is measured while the sound, voice and language from thesound stimulation controller and the image data from the visualstimulation controller are read from the speaker or headphone and theimage display device to present them to the subject.

13) The brain function measurement instrument according to the 12),wherein the speaker or headphone and the image display device readingstimulation and presenting it to the subject are integrally provided ina bed or incubator in which the subject lies.

14) The brain function measurement instrument according to the 12),wherein a fixing part fixing the subject in the bed in which the subjectlies is slant.

15) The brain function measurement instrument according to the 12),wherein the speaker or headphone is provided in the fixing part fixingthe subject in the bed or incubator in which the subject lies.

16) The brain function measurement instrument according to the 12),wherein the image display device is fixed in the position notimmediately above the subject in the bed or incubator in which thesubject lies.

17) The brain function measurement instrument according to the 12),wherein the fixing part fixing the subject has a member supporting thelegs of the subject.

18) The brain function measurement instrument according to the 12),wherein the fixing part fixing the subject in the bed in which thesubject lies has members supporting the head and the neck of the subjectso as to release the back part of the head.

19) The brain function measurement instrument according to the 12),wherein the fixing part fixing the subject in the bed in which thesubject lies is slant, has a member supporting the legs of the subject,and has members supporting the head and the neck of the subject so as torelease the back part of the head.

20) The fixing part fixing the subject according to the 17), wherein themember supporting the legs of the subject is movable.

21) The fixing part fixing the subject according to the 18), wherein themembers supporting the head and the neck of the subject is movable tochange the shape.

22) A brain function measurement instrument having a biological opticalmeasurement instrument having illuminating means for illuminatingbiological tissue and light collecting and detecting means forcollecting and detecting light transmitted through the biologicaltissue, a brain wave measurement instrument measuring brain waves, asound stimulation controller having a plurality of data about sound,voice and language, a speaker or headphone presenting the sound, voiceand language to a baby subject, a visual stimulation controller having aplurality of data about image, and an image display device presentingthe image to the subject, wherein the biological optical measurementinstrument, the brain wave measurement instrument, the sound stimulationcontroller and the visual stimulation controller are in synchronizationwith each other for transmitting and receiving a signal of timing, time,length and the kinds of stimulation presenting sound, voice, languageand image stimulation, reading the sound, voice, language and image datafrom the sound stimulation controller and the visual stimulationcontroller in synchronization with the signal from the speaker orheadphone and the image display device, and presenting them to thesubject.

INDUSTRIAL APPLICABILITY

According to the present invention, the probe for the measurement ofbiological tissue with light based on the present invention readilywearable on a biological surface having a large curvature can measurethe psychological change in the head or the motion portion such as thearm of a newborn or a baby, which has been difficult to measure.

Since the brain functions of a baby including a newborn can be measured,the brain disorders of the baby can be found at an early stage. Inparticular, the brain wave measurement and the measurement with lightare united to simultaneously measure both the brain deep part and thecerebral cortex, realizing total brain function measurement andfacilitating decision of the brain functional disorders.

According to the present invention, the application field of themeasurement of biological tissue with light is expanded andsignificantly contributes to the industry. In particular, understandingof the development process of the brain functions contributes to thefield exerting a significant influence on the society such as education.

1. A biological measurement probe comprising illuminating means forilluminating the head of a subject through a plurality of opticalwaveguides and light collecting means for collecting light illuminatedfrom said illuminating means and propagated through the subject througha plurality of other optical waveguides; a plurality of opticalwaveguide fixing parts each having a plurality of optical waveguidefixing members for fixing the plurality of optical waveguides; aplurality of holding parts holding and covering the plurality of opticalwaveguide fixing parts, said plurality of holding parts beingconstructed with extensible belts or strings, and pressing the pluralityof optical waveguides to the head of the subject when the probe isinstalled on the head of the subject; and a plurality of connectingparts connecting respective holding parts.
 2. The biological measurementprobe according to claim 1, wherein the optical waveguide fixing membersare arranged on the optical waveguide fixing parts in such manner thatthe optical waveguides for illumination and the optical waveguides forcollection are alternately disposed on top positions of a square gridshape or a rhombus grid shape.
 3. The biological measurement probeaccording to claim 1, wherein the illuminating means includes a lightsource for illumination and a light source control circuit controllingan injected current to the light source, and the light collecting meansincludes an optical detector and a detection signal circuit processing adetection signal obtained by the original detector.
 4. The biologicalmeasurement probe according to claim 1, wherein the optical waveguidefixing members are each provided with an internally disposed electrodefor brain wave measurement together with the optical waveguide so as tosimultaneously make the measurement with light and the brain wavemeasurement.
 5. The biological measurement probe according to claim 1,wherein the cross-section area of the optical waveguides at the sidecontacting to the head of the subject broadens as approaching the endsurface of the optical waveguides.
 6. A biological optical measurementinstrument, comprising: a biological measurement probe havingilluminating means for illuminating the head of a subject through aplurality of optical waveguides and light collecting means forcollecting light illuminated from said illuminating means and propagatedthrough the subject through a plurality of other optical waveguides,comprising: a plurality of optical waveguide fixing parts each having aplurality of optical waveguide fixing members for fixing the pluralityof optical waveguides, and a plurality of holding parts holding andcovering the plurality of optical waveguide fixing parts, said pluralityof holding parts being constructed with extensible belts or strings, andpressing the plurality of optical waveguides to the head of the subjectwhen the probe is installed on the head of the subject, and a pluralityof connecting parts connecting respective holding parts, wherein theoptical waveguide fixing members are each provided with an internallydisposed electrode for brain wave measurement together with the opticalwaveguide so as to simultaneously make the measurement with light andthe brain wave measurement, and stimulation presenting means forpresenting a stimulation to the subject.
 7. The biological opticalmeasurement instrument according to claim 6, further comprising a bed onwhich the subject lies down.
 8. The biological optical measurementinstrument according to claim 7, further comprising a fixing part forfixing the subject in the bed.